1. Field of the Invention
The present invention relates to a transfer type image building apparatus in which an image is built on material such as copying paper or the like by transferring a coloring agent to the surface of material and, more particularly, to an improvement of or relating to an image building apparatus of the type including guiding means for the purpose of guiding material adapted to reciprocably move through a transferring section to carry out superimposing transferrence, wherein the apparatus makes it possible to carry out transferrence to both surfaces of the material in spite of simple structure.
2. Description of the Prior Art
A thermal transfer type image building apparatus is well known as transfer type image building apparatus in which an image is built on material such as copying paper or other printing medium by transferring a coloring agent to the surface of material. As characterizing features of thermal transfer type image building apparatus that it is small in dimension and inexpensive in manufacturing cost, it generates less noise and any type of plain paper can be used as material to which coloring agent is to be transferred are increasingly recognized, it is being widely put in practical use not only for the purpose of recording output from a word processor, computor or the like but also as a copying machine in recent years.
This type of image building apparatus is usually constructed such that paper is delivered to the area as defined between a platen and a thermal head and the latter is then brought in pressure contact with the platen with an ink ribbon interposed therebetween so that an image is transferred to the surface of paper. In recent years a modified type of image building apparatus has been developed which assures superimposing transferrence by allowing the paper to reciprocably move relative to the thermal head. Further, another modified type of image building apparatus has been developed which assures not only superimposing transferrence but also image transferrence to both the surfaces of the paper.
The conventional image building apparatus which makes it possible to carry out both superimposing transferrence and image transferrence to both surfaces of the paper is generally constructed such that on completion of superimposing transferrence to one surface of the paper the latter is delivered to a paper upsetting passage arranged specially in the housing of the apparatus and upset paper is brought back to the thermal head so as to carry out image transferrence to the other surface of the paper. However, it has been found that the conventional image building apparatus has drawbacks that due to the special arrangement of the paper upsetting passage in the housing, the apparatus is complicated in structure and expensive in manufacturing cost and it takes a long time until the paper is upset in the passage because the latter has a long length.